Dressings, spreads, sauces and other oil and water emulsion based products are well known. Over the years the number of different variants that is available for such emulsions has grown. When made at home, consumers can make their personal dressing or sauce variant and add the desired ingredients to match their liking. There is also a trend in society to obtain a ready meal or parts of the meal from a restaurant or store without the need to do any cooking activity yourself. It is evident that the variety provided via a restaurant, store or other retail outlet is limited because of the amount of time it takes to make personalized emulsion type products. Also the amount of product purchased if a large variety is offered is very low, and often too low to justify the preparation of each particular variant.
U.S. Pat. No. 6,280,075 discloses a plant for continuously preparing at least two different liquid foodstuff mixtures. This document addresses the problem that for the preparation of a variety of beverages in a factory, plant portions which treat basically mixture components, e.g. in case of beverages water and sugar solution, must be present two fold or in a plurality of numbers, causing correspondingly high procurement and operating costs. According to US'075 this problem is solved by a plant system in which only one single plant portion is needed for the mixture components, which is common to the several foodstuff mixtures. In one embodiment, each product has dedicated mixers, buffers and filling machines. Hence the variety of product prepared in such plant is still limited. Variation within a certain recipe is not possible. A change of recipe means that all mixers, buffer tanks and the filling machine have to be cleaned to avoid contamination of the next product. In another embodiment, all product variants use a common mixer. This mixer needs cleaning for each recipe switch.
Another existing desire is the desire for fresh products. Food products that are prepared in a factory may not fulfill this desire and hence methods have been developed to provide food products, e.g. emulsions that are prepared on the spot from their raw ingredients, mainly oil and water.
Furthermore providing a particular product variant may cost a lot of time for preparation, which is undesired for the consumer who may wish to take or consume the product immediately.
To overcome the latter problems, ways have been developed which provide a metered amount of emulsion, prepared instantaneously and if desired on demand. Instant in this context is referring to “on the spot”, within a short time in the order of seconds to minutes. An example of a suitable dispensing unit is disclosed in WO-A-01/00521. The dispensing unit disclosed therein is a bottle which stores two or more separate fluids and blends the fluids when dispensing. The two fluids may be oil and vinegar to prepare dressings. The amount of different products that may be prepared using such a dispenser is rather limited and the most advantageous property of this unit is that it enables creating a fresh emulsion instantaneously.
Furthermore the size of this dispensing unit, which is manually operated, is not enabling efficient preparation of individually adapted emulsion type products instantaneously for example in a fast food service restaurant.
U.S. Pat. No. 5,230,443 addresses the need for a reliable, relatively inexpensive apparatus and method for dispensing a variety of condiments through a single dispensing unit in a metered quantity and at a low flow rate. Providing a device, which comprises a pump, which is fluidly connected to a condiment source and a dispensing apparatus, solves this need. Multiple pumps (e.g. 3) may be included wherein each pump is connected to a different condiment source. This enables independent dispensing of e.g. 3 different types of condiment. Again this offers only limited variety and requires a separate condiment source for each type of condiment offered. Also the products obtained from this device are not fresh products.
One of the known problems associated with apparatus' that provide a variety of products with different recipes is cross contamination between products that are of different composition but dispensed through the same nozzle. U.S. Pat. No. 4,753,370 discloses a mixing nozzle that can mix different flavours into a product stream, without cross contamination. This is achieved by mixing the flavour in-line into a flowing aqueous stream wherein the flavour is injected such that the flavour does not touch any of the nozzle housing. This solution may be suitable for low viscosity beverages wherein homogeneous mixing is relatively easy but was found to be unsuitable for homogeneously mixing oil and water compositions which are more viscous. Generally oil and water emulsions are either pourable or spoonable and the higher the viscosity, the more cross contamination may be occurring.
In summary the flexibility provided by the prior art devices is low. Either the known dispensers are fed with finished products and only able to deliver this on demand, or the instant preparation of product delivers fresh product with no or limited variety in product composition or high contamination when switching to a new variety.
Therefore it is an object of the invention to provide an apparatus, which dispenses a variety of products without the need to clean and rinse the entire apparatus on switching to a different variety.